In an air conditioner, it is known to provide flap-shaped air mixing members (control flaps) between an evaporator which cools air passing therethrough, and a heating heat exchanger (e.g., heater core) which heats air passing therethrough. By adjusting the operation positions of the control flaps, the cold air from the evaporator and the warm air from the heating heat exchanger are mixed to have a desired temperature before air is supplied to a passenger compartment. In this case, the flow directions of the cold air and warm air relative to one another are changed according to the adjustment of the control flaps, so that conditioned air having different conditions (e.g., temperature) can be obtained. Further, due to the arrangement of the control flaps between the evaporator and the heating heat exchanger, it is difficult to set very different temperature ranges in the front and rear areas of the passenger compartment.